"The Case Against 8," a documentary tracing the fight to keep gay marriage legal in California, premieres on HBO Monday, June 23, the first anniversary of the landmark Supreme Court ruling.

The documentary, already a film festival favorite, looks at the battle to overturn Prop 8, which made gay marriage illegal in California. It shows the people behind what had become a complicated and vitriolic argument: what constitutes a marriage.

The film focuses on two couples, one male, one female.

They're loving, thoughtful and sincere, which is why they were picked. By the time the couples wed, the women in San Francisco, the men in Los Angeles, it would take a pretty hard-hearted viewer to not tear up.

All they had wanted all along were to be granted equal rights. Eventually the Supreme Court guaranteed that.

Ted Olson, a longtime attorney for Republican causes and who was pivotal in the 2000 Gore v. Bush decision, champions the case to allow gay couple to marry.

"Marriage is a conservative value," Olson says on screen. "It's two people who love one another and want to live together in a stable relationship, to become part of a family and part of a neighborhood and part of our economy. We should want people to come together in marriage."

Filmmakers Ben Cotner and Ryan White had tremendous access. They show how much Kris and Sandy, the moms of four sons, and Paul and Jeffrey are in love.

That, naturally, is the point and why everyone fought so hard.

Despite the importance of the issue, and how genuine everyone is, the film is extremely slow. Watching lawyers and plaintiffs wait for a decision, watching people get ready or the changing light on the Golden Gate Bridge, no matter how majestic, does not improve its pace.

The subject matter alone warrants attention, and it's worth noting, as the film does at the end, that same sex marriage remains illegal in 33 states.